Catch OperationCanceledException in both command loops (#1850)

Our flaky extension command test seems to be flaky because sometimes
another task gets queued, and since it runs in the foreground it cancels
that task. Interactively, this happens in the first loop (with
`DoOneRepl`) which catches the cancellation exception; but when under
tests that is a no-op, so it happens in the second loop. Hence we should
duplicate the same logic and so catch that exception.

Author: andyleejordan

src/PowerShellEditorServices.Hosting/Commands/StartEditorServicesCommand.cs

@@ -228,8 +228,10 @@ protected override void EndProcessing()
 
                 using EditorServicesLoader psesLoader = EditorServicesLoader.Create(_logger, editorServicesConfig, sessionFileWriter, _loggerUnsubscribers);
                 _logger.Log(PsesLogLevel.Verbose, "Loading EditorServices");
-                // Start editor services and wait here until it shuts down
+                // Synchronously start editor services and wait here until it shuts down.
+#pragma warning disable VSTHRD002
                 psesLoader.LoadAndRunEditorServicesAsync().GetAwaiter().GetResult();
+#pragma warning restore VSTHRD002
             }
             catch (Exception e)
             {

src/PowerShellEditorServices/Services/PowerShell/Host/PsesInternalHost.cs

@@ -771,7 +771,14 @@ private void RunExecutionLoop(bool isForDebug = false)
                     && !cancellationScope.CancellationToken.IsCancellationRequested
                     && _taskQueue.TryTake(out ISynchronousTask task))
                 {
-                    task.ExecuteSynchronously(cancellationScope.CancellationToken);
+                    try
+                    {
+                        task.ExecuteSynchronously(cancellationScope.CancellationToken);
+                    }
+                    catch (OperationCanceledException e)
+                    {
+                        _logger.LogDebug(e, "Task {Task} was canceled!", task);
+                    }
                 }
 
                 if (_shouldExit

test/PowerShellEditorServices.Test/Extensions/ExtensionCommandTests.cs

@@ -33,7 +33,9 @@ public ExtensionCommandTests()
                 serviceProvider: null,
                 editorOperations: null,
                 executionService: psesHost);
+#pragma warning disable VSTHRD002
             extensionService.InitializeAsync().Wait();
+#pragma warning restore VSTHRD002
             extensionCommandService = new(extensionService);
         }
 
@@ -110,7 +112,8 @@ await psesHost.ExecutePSCommandAsync(
             Assert.Equal(commandName, commandAdded.Name);
             Assert.Equal(commandDisplayName, commandAdded.DisplayName);
 
-            // Invoke the command
+            // Invoke the command.
+            // TODO: What task was this cancelling?
             await extensionCommandService.InvokeCommandAsync("test.scriptblock", editorContext).ConfigureAwait(true);
 
             // Assert the expected value